Screening and Selection of Media Components for Protease Production by Bacillus sp. EBTA6 Using Plackett–Burman Design

In this study, effects of medium components and inoculum size on the protease production by Bacillus sp. EBTA6 that was isolated from a home-made Tarhana sample were investigated. The cell-free supernatant of bacterium cultured on a shaking incubator for 24 h was used to test protease activity as the response. With a total number of 11 factors, 12 different experiments were run and the highest experimental protease activity was measured as 2280.4 U/mL. Results were analyzed statistically by ANOVA and the most efficient factors were detected as yeast extract, dipotassium phosphate, casein, and peptone with a contribution of 93.78, 2.19, 1.96, 1.31%, respectively. For validation of the selected factors, a further experiment was performed by using of yeast extract (9.98 g/L), dipotassium phosphate (1.27 g/L), casein (8.69 g/L), and peptone (9.88 g/L) obtained from the design equation. The experimental response was found as 2411.4 U/mL which was only 5.5% higher than the predicted response showing that the model was applicable.